The soap's boss told DS that the popular couple, played by Ricky Whittle and Gemma Merna, will continue to be at the forefront of the show in 2010.
Viewers have recently seen Calvin experiencing a growing attraction to Carmel's sister Mercedes, played by Jennifer Metcalfe.
However, Allan teased: "There's a lot going on with the McQueens. Calvin's having an affair with Mercedes at the minute, but we'll be toying with Calvin and Carmel's romance once again - could they reunite?
"I believe that they've always been in love and have never stopped loving each other. I've had conversations with Ricky and Gemma and we've talked about the fact that Calvin and Carmel should always give each other loving looks and always be on the lookout for each other.
"Mercedes is the devil on Calvin's shoulder, while Carmel's the angel. Does he deserve the angel? Or will he stick with the devil?"
Earlier this year, Merna revealed that she "loves" the relationship between Carmel and Calvin and had been "wishing" for a reunion.
> Click here to read Lucy Allan's Producer's Perspective 2009
> Click here to read what's to come in Hollyoaks in 2010